Bituminous emulsions and method of producing same



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Patented Oct. 1, 1940 BITUMINOUS EMULSKONS AND METHOD OF PRODUCING SAME William N. Davis, Orville E. Cushman, and Joseph E. Fratis, Berkeley, Calif., assignors to Stand ard Oil Company of California, San Francisco, Calif., a corporation of Delaware i No Drawing. Original application May 28, 1934,

" Serial No. 727,894, now Patent No. 2,132,607,

dated October'll, 1938. Divided and this application May 21-, 1938, Serial No. 209,358

13 Claims.

This invention relates to slow breaking bitumen-in-wateremulsions, suitable for mixing with aggregates and the like, and to methods for preparing the same.

This application is a division of our co-pending application Serial No. 727,894, filed May28, 1934, which has matured into Patent No. 2,132,607 issued October 11, 1938. In the said application Serial No. 727,894 we make claim to theproces s, described hereinafter, of stabilizing quick-breaking bituminous emulsions through the addition thereto of sulfate pulp process black liquor and acid reacting polyhydric phenols and to the stabilized emulsions produced thereby; in the present divisional application we make claim to the described process and product in whichthe acid reacting substances are certain inorganic salts.

The practice of adding variously chosen materials to the ordinary quick breaking bituminous emulsions of commerce to render them-less quick breaking and thus mixable with aggregates, applicable as paints by brushing and for various similar uses is well known. Soaps such as the alkali soaps of the fatty acids, proteins such as casein and gelatine or their alkali compounds, colloidal clays such as bentonite and certain inorganic salts such as trisodium phosphate have all received some consideration in this connection.

All of these materials are, however, to a certain degree primary emulsifiers and are not essentially stabilizers. They therefore appear to impart stability to quick breaking emulsions merely by promoting further emulsification and not by any stabilizing function peculiar to themselves. .Whether or not this be the reason it is a fact that in one way or another the slow breaking emulsions prepared through the use of such materials have usually fallen short of the desired perfection. They are either too viscous, too' costly, too subject to attack by organisms, too readily reemulsified or are not sufficiently stable. For instance, few emulsions ofthis-type have ever been produced which could be mixed with aggregates containing high percentages of Portland cement without immediate and substantially complete breakdown. i

It is the object of this invention to provide a stabilizer for quick breaking bitumen-in-water emulsions which will possess none of the foregoing defects. i

It is another object of this invention to provide a means for producing mixing type emulsions of a wide range of oleaginous materials and of any constitute a major portion of the non-cellulosic desired degree of stability or rate of breakdown.

Another object is to provide bituminous emulsionswhich are non-viscous and free flowing even in concentrated form and which are of extreme stability when mixed with substantial quantities 5 of Portland cement. g A further object is to provide anemulsion stabilizer for use in oil-in-water type emulsions which is readily available at low cost.

A still further object of our invention is to provide an economical use for a considerable quantity of what has hitherto been a waste product of the paper pulp industry.-

Still other objects ofour invention" will be readily apparent to those skilled in the art from the description and discussion which follows. Y

As'it is well known, the primary object in the preparation of paper pulp from wood is to decompose the complex and poorly understood combinations of cellulose with a host of associated ingredients and to isolate the cellulose in substantially pure form with but littleconcern as to what changes are broughtabout in the associated materials during the process. Several methods have been devised and widely adopted for effecting this primary object though they arrive at the desired end by quite different chemical routes with the-result that the bodies with which the cellulose was originally associated are found to emerge from the several processes in very different states'of combination and consequently with quite different properties and utility.

For instance in the widely used acid sulfite process the lignin orlignone complexes, which ingredients of wood, emerge as Water soluble sulfonic acids and/or sulfonic acid salts and remain in the so-called waste liquor a'ssuch. On the other hand, in the alkaline soda" and sulfate processes these same lignincomplexes are convertedto water soluble salts of what have been loosely termed lignic acids.-

Similarly'the resin bodies, thehemicelluloses,

.the sugars, the proteins and the fats of .the

original wood are quite differently affected by the acid and by the alkaline methods of cellulose liberation so that the waste liquors from these two types of process are quite difierent in substantially every respect. y

It is however not surprising since the primary or main product, cellulose, is substantially'the same from the several processes, that but little attention has been paid to the foregoing fundamental dififerences which exist between the secondary products, and further the cellulose- It is further a fact, that appears to have been all too infrequently recognized, that from the same process of decomposition somewhat different waste liquors will result from the treatment of different kinds of woods and even from the same process and the same-wood through different specific procedure in individual instances.

The net result is, therefore, that many hazy, confused andeven conflicting statements are to be found scattered throughout the literature rela-. tive to the properties and hence the potential uses of this or that waste liquor from the wood pulpindustry. The literature covering the art of bituminous emulsion manufacture has been beset with a particularly impressive array of such assertions, chief among which is'to the effect that the liquors from the acid sulfite process either as such or when neutralized or in other modified forms constitute powerful and hence highly desirable primary emulsifiers. The alkaline or black liquors from the soda and the sulfate processes have likewise, though less frequently, been proposed as possessing primary emulsifying powers of a high order.

During an extended study of both the sulfite and the sulfate waste liquors and particularly of their action and the action of their various components in bituminous emulsion systems we have found that while most of the previous disclosures are either wrong or require very considerable interpretation and modification ,tomake them operable there is atleast one fact which, so far as we are aware, has not previously beendisclosed and which appears to constitute a major contribution to the art of bituminous emulsion, manufacture as well as to provide that for which so many workers have previously sought, namely, a useful outlet for one of the waste products of the wood pulp industry. v 1

We have discovered that if the alkaline "black liquor" from the "sulfate process is properly employed a stabilizer of very great potency for already formed oil-in-water type bituminous emulsions may be produced.

As is well known in the industry, but .a few methods have hitherto been available for the production of asphaltic emulsions which could be mixed with aggregates carrying useful quantities of finely divided solids and especially of Portland cement without substantially immediate and complete breakdown of the emulsion. The advantages inherent in a concrete containing both Portland cement and a bituminous binder have, therefore, seldom been realized. Especially has this been true when it has been necessary or expedient to employ asphalts derived wholly from petroleum and in the absence of an appreciable amount of added natural asphalt such as that from Trinidad.

Our invention consists'broadly in oil-inwater type emulsions of extreme. stability, and in a method for their, production, with particular emphasis on petroleum asphalt emulsions having a degree of stability or resistance to breakdown sufficient to permit of thorough mixing with aggregates containing relatively high percentages of Portland cement or other highly subdivided uct.

solids, and in a simple and reliable means for producing the same.

Our stable emulsions, contrary to general previous practice, do not derive their stability from large amounts of primary emulsifier added in excess of the amount necessary to initially produce the emulsion and in fact often contain no priscribed by Montgomerie in U. S. #1,643,6'75 or by Braun in U. 5. #1,737,491. While the temperature of this emulsion is held at 160-210 F. and preferably at 180-190 F. we add with constant stirring the desired quantity of sulfate black liquor, containing roughly 15% solids,

followed immediately by .a solution of one of several acidic bodies in quantity sufficient to bring the finished composition to substantial neutrality or even to make it slightly acid.

, Ifagitation is interrupted as soon as the black liquor stabilizer and the acidic neutralizer are thoroughly incorporated and the composition is allowed to cool in a substantially quiescent state, preferably in the mixer in which prepared, an emulsion entirely unique in certain of its prop erties will result. I y

In the selection of a suitable black liquor or black liquor concentrate for use in this connection it appears to make little difference whether the resin and fatty acid soaps formed by hydrolysis during treatment of the wood have been removed, as is the practice in some mills, or whether the total organic decomposition prod- .ucts remain in the liquoras produced. Similarly it appears, so far as we have yet found, that the particular kind of wood from which the black liquor is derived is of minor importance in determining the stabilizing power of the prod- The quantity of black liquor to be used for imparting greatest stability to an emulsion is, on the other hand, extremely critical. For instance with one liquor which may be considered typical of that produced in the Pacific Northwest we havefound that the operable range lies between 3 and 4% of blackliquor (15% solids) on the basis of the finished emulsion, which calculated to black liquor solids. shows an operable range from 0.45 to 0.60% of the emulsion. Since these solids will contain at least 35% ash it will be seen that the limits of concentration for the actual organic stabilizer will be from about 0.30 to about 0.40% of the emulsion. In one typical instance we found 0.578% total solids to be the optimum amount for use with a asphalt, Braun emulsion.

While in such an-obviously delicately balanced system it would of course be impossible to set an exact concentrationof stabilizer which could be taken as universal, the operable range is so narrow that it will not be diillcult fora skilled operator to determine the amount most suitable for his particular combination of materials and his specific purpose.

In the selection of satisfactory acidic mate- I rials for use in our invention we have found a considerable number of inorganic salts giving acidic water solutions and also several weak organic acids to be operable and-have usually emthe quick breaking emulsion, the residual alkalinity-of the black liquor and to bring the aqueous phase as a whole to apH of 5.5 to 7.0.

While black liquors may be used with good results in our process in the form in which'they are received from the pulp mills lt will sometime be desirable first to remove as far as possible any resin acid and fatty acid soaps which'may be present since if allowed to remain the'ywill use up a certainamount of the acidiiier subsequently added" and'thus increase the amount necessary to reach the desired pH. Similarly it is not necessary to remove the rather considerable amounts of alkalicarbonate usually contained in black liquors but when such is done by acidifying with a-cheap mineral acid and then 'returningthe liquor to an alkaline condition before use it' will be found that by such procedure the overall cost of stabilizing an emulsion is appreciably reduced and operating difficulties due to the slow liberation of carbon dioxide inthe stabilized emulsion are completely eliminated. V

The relative values of several materials tested inthis connection are clearly set out in the following table of results obtainedby applying the so-called Cement Test as a measure of the emulsion stability: I I

Cement test.-Thoroughly 2% parts of sand and 7 parts of Portland cement and then mix in 20 parts of emulsion. The stability of the emulsion is judged by its abilityv to incorporate or absorb the solids without breaking.

, In considering. these several acidiflers it will be noted that of the organic acids tested all that we found operable contain at least one benzene nucleus carrying at least two hydroxy groups, Since tannic acid proved to be the best such acid it, further appears that the larger-the number of OH groups onv the aromatic nucleus the more efiective is the acid in bringing about the stabilizing action of the black liquor. should be so is, however, not yet apparent.

In an attempt to better understand this rather surprisingemulsion stabilizing action of the alkaline black liquors from the sulfatepulp process weyhave'carried out a number of comparative tests in which a liquor from the acid sulflte process was employed. .This liquor was tested in its original acid condition, when neutralized and when made slightly alkaline each, both with and without the addition of the more active acidifiers Just why this such as alum and tanic acid which had been' found so effective in causing the sulfate liquor to exert its stabilizing action. In no case were we successful in causing a sulfite liquor to show the slightest stabilizing action whatever.

In order to throw further light on the action of the waste liquors from these two major pulp processes in bituminous emulsion systems we have tested both in various comparable forms' as prlmary emulsifiers. We have found the sulfite liquors generally to have moderate emulsifying power while the sulfate liquors appear to have n such power whatever.

As a result of these and others tests we have arrived ata theory'as to the mechanism by which the action of the sulfate liquors, upon which our invention rests, is brought about. It is our belief that lignic acid complexes are liberated from their water soluble salts which occur in the sulfate process liquors when these liquors are made acid and further that, since all acids or acid bodies used in this connection do not give emulsion sta tated as appears to be the case with the sulfate black liquor.

Whether or not this be the correct explanation of our discovery the fact remains that extremely stable emulsions can be prepared through the proper addition of relatively small-quantities of black liquor to preformed, quick breaking emulsions.

Our emulsions, so'stabilized, possess an entirely unique combination of properties the mere recitation of which will suggest to those skilled in the art a wide-variety of desirable uses for which suitable asphalticernulsions have hitherto seldom if ever been available.

They possess a degree of fluidity which is equal to and in some cases even greater than that of the quick breaking emulsions from which they are produced. This insures easy-and complete mixability with aggregates or other desirable fillers and is in sharp contrast to the high viscosity of previous emulsions of equal bitumen content and equal stability.

They carry so little primary emulsifier that once broken they do not re-emulsify as do the slow breaking emulsions prepared through the use of large amounts of primary emulsifiers.

They are mixable with any desired quantity of carbon black, a property possessed by no other "emulsion of which we are aware, and are thus useful in the preparation of ahigh grade of asphaltic paint. I

They are neutral or slightly acid, a condition hitherto unknown in emulsions of equal stability, and are thus useful in many combinations in which the customary alkaline emulsion would be entirely unsuited. They may, for this reason, be incorporated'with the ordinary vegetable drying oils in the preparation of asphaltic enamels, whereas these oils in an alkaline medium would readily form soaps and hence lose their desired utility.

One final advantage inherent in these emulsions is the very small quantity of widely available materials which it is necessary to employ in additionto the primary constituents in order to secure the full advantages of maximum stability.

While our description and discussion has centered particularly around asphaltic emulsions it is perfectly obvious that our emulsion stabilizer would function in other .oleaginous dispersions which are therefore to be considered a part of our invention and within the scope of the. appended claims.

Having now fully described our invention and how it may be utilized what we claim is:

1. An emulsion of asphalt in. water containing substantially no primary emulsifier other than soaps formed from the asphaltic acids inherent in the asphalt, said emulsion being stable when mixed with as much as 10% of its weight of Portland cement and comprising a small proportion of black liquor from the sulphate pulp process and an acid reacting inorganic salt selected from the group consisting of aluminum sulphate, alum, ferric sulphate, ferrous sulphate, antimony chloride, zinc chloride and silver nitrate.

2. An emulsion of asphalt in water as in claim 1 wherein the pH of the aqueous phase is between about 7.0 to 5.5.

3. A fluid. mixing type bituminous emulsion resulting from the stabilization of a normally quick-breaking emulsion through the addition thereto of a quantity of black liquor from the sulphate pulp process sufficient to provide about 0.3 to 0.4% by weight, based on the emulsion, of the organic stabilizer portion of said black liquor and an acid reacting inorganic salt to bring the pH of'the emulsion to about 7.0 to 5.5, said salt being selected from the group consisting of aluminum sulphate, alum, ferric sulphate, ferrous sulphate, antimony chloride, zinc chloride and silver nitrate.

4. A fluid, mixing type bituminous emulsion resulting from the stabilization of a normally quickbreaking emulsion through the addition thereto of a quantity of black liquor from the sulphate pulp process sufficient to provide about 0.3 to 0.4% by weight, based on the emulsion, of the organic stabilizer portion of said black liquor and aluminum sulphate to bring the pH of the emulsion to about.'7.0 to 5.5.

5. A fluid, mixing type bituminous emulsion resulting from the stabilization of a normally quickbreaking emulsion through the addition thereto of a quantity of black liquor from the sulphate pulp process sufficientto provide about 0.3 to 0.4% by weight, based on the emulsion, of the organic stabilizer portion of said black liquor and ferric sulphate to bring the pH of the emulsion to about 7.0 to 5.5.

6. A fluid, mixing type bituminous emulsion resulting from the stabilization of a normally quickbreaking emulsion through the addition thereto of a quantity of black liquor from the sulphate pulp process sufilcient to provide about 0.3 to 0.4 by weight, based on the emulsion. of the organic stabilizer portion of said black liquor and zinc chloride to bring the pH of the emulsioh to about 7.0 to 5.5.

'7. A stable, slow-breaking, fluid emulsion of asphalt in water comprising a normally quickbreaking emulsion stabilized by the presence of a minor proportion of a sulphate process black liquor and an acid reacting inorganic salt effective to bring the pH of the emulsion to within the range of from about 7.0 to about 5 .5 and adapted to co-act therewith in preventing breakdown of the emulsion, said emulsion containing a proportion of carbon black which without said sulphate process black liquor and. said acidreacting inorganic salt would break said emulsion. 8. A method 'of producing va slow-breaking, mixing type bituminous emulsion, which comprises adding to a relatively quick-breaking emulsion normallyunstable when 20 parts by weight thereof are contacted, with a mixture of 2 /2 parts of sand and 71/2 parts of Portland cement, a small proportionof a sulphate pulp process black liquor followed immediately by the step of adding to the admixture an acid reacting inorganic salt effective tobring the pH of said emulsion to within the range offrom about 7.0 to about 5.5 and adapted to co-act with the black liquor material in rendering the emulsion stable when 20 parts by weight thereof are contacted with a mixture of 2 parts of sand and 7 parts of Portland cement. I i i 9. The method of producing a-slow-breaking asphalt'ic emulsionwhich comprises addingtoa relatively quick-breaking emulsion a quantity of black liquor from the'sulphate pulp process sufficient to provide about'0.3 'to 0.4% by weight, based'on the-emulsion, of the organic stabilizer portion of said black liquor followed immediately by an acid reacting inorganic salt to bring the pH of the emulsion to about 7.0 to 5.5, said salt being selected from the group consisting of aluminum sulphate, alum, ferric sulphate, ferrous sulphate, antimony chloride, zinc chloride and silver nitrate.

10. The method as in claim 9 wherein the black liquor stabilizer is vigorously stirred into the quick-breaking emulsion, heated to about to 210 F. and the acidic material is added'immediately thereafter with further agitation.

11. The method of producing a slow-breaking asphaltic emulsion which comprises adding to a relatively quick-breaking emulsion aquantity of black liquor from the sulphate pulp process sufllcient to provide about 0.3 to 0.4% by weight, based on the emulsion, of the organic stabilizer portion of said black liquor followed immediately by an amount of aluminum sulphate to bring the pH of the emulsion to about 7.0 to 5.5.

12. The method of producing a slow-breaking 'asphaltic emulsion which comprises adding to a relatively quick-breaking emulsion a quantity of black liquor from the sulphate pulp process sufficient to provide about 0.3 to- 0.4% by weight, based on the emulsion, of the organic stabilizer portion of saidblack liquor followed immediately by an amount of ferric sulphate to bring the pH of the emulsion to about '7.0to'5.5.

13. The method of producing a slow-breaking asphaltic emulsion which comprises adding to a relatively quick-breaking emulsion a quantity of black liquor from the sulphate pulp process sufiicient to provide about 0.3 to 0.4% by weight, based on the emulsion, of the organic stabilizer portion of said black liquor followed: immediately by an amount of zinc chloride to bring thepH of the emulsion to about 7.0 to 5.5.

. ORVILLE E. CUSHMAN.

JOSEPH E. F'RATIS. WILLIAM N. DAVIS. 

